package guojin.sqlsession;

import guojin.pojo.Configeration;
import guojin.pojo.MappedStatement;

import java.lang.reflect.*;
import java.util.List;

/**
 * @author haoge
 * @version $Id DefaultSqlSession.java, v 0.1 2021-06-12 22:07 haoge Exp $$
 */
public class DefaultSqlSession implements SqlSession {
    private Configeration configeration;

    public DefaultSqlSession(Configeration configeration) {
        this.configeration = configeration;
    }

    @Override
    public <T> List<T> selectList(String statementid, Object... params) throws Exception {

        //将要去完成对simpleExecutor里的query方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configeration.getMappedStatementMap().get(statementid);
        List<Object> list = simpleExecutor.query(configeration, mappedStatement, params);
        return (List<T>) list;
    }

    @Override
    public <E> E selectOne(String statementid, Object... params) throws Exception {
        List<Object> objects = selectList(statementid, params);

        if (objects.size() == 1) {
            return (E) objects.get(0);
        } else {
            throw new RuntimeException("返回值不能为空或者多条");
        }
    }

    @Override
    public <E> int addUser(String statementid, Object... params) throws Exception {
        //将要去完成对simpleExecutor里的query方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configeration.getMappedStatementMap().get(statementid);
        int o = simpleExecutor.insert(configeration, mappedStatement, params);
        if (o > 0) {
            return o;
        } else {
            throw new RuntimeException("添加数据失败");
        }
    }

    @Override
    public <E> int updateUser(String statementid, Object... params) throws Exception {
        //将要去完成对simpleExecutor里的query方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configeration.getMappedStatementMap().get(statementid);
        int o = simpleExecutor.insert(configeration, mappedStatement, params);
        if (o > 0) {
            return o;
        } else {
            throw new RuntimeException("添加数据失败");
        }
    }

    @Override
    public <E> int deleteUser(String statementid, Object... params) throws Exception {
        //将要去完成对simpleExecutor里的query方法的调用
        SimpleExecutor simpleExecutor = new SimpleExecutor();
        MappedStatement mappedStatement = configeration.getMappedStatementMap().get(statementid);
        int o = simpleExecutor.insert(configeration, mappedStatement, params);
        if (o > 0) {
            return o;
        } else {
            throw new RuntimeException("添加数据失败");
        }
    }

    @Override
    public <T> T getMapper(Class<?> mapperClass) {
        // 使用JDK动态代理来为Dao接口生成代理对象，并返回

        Object proxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                // 底层都还是去执行JDBC代码 //根据不同情况，来调用selctList或者selectOne
                // 准备参数 1：statmentid :sql语句的唯一标识：namespace.id= 接口全限定名.方法名
                // 方法名：findAll
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementId = className + "." + methodName;

                // 准备参数2：params:args
                // 获取被调用方法的返回值类型
                Type genericReturnType = method.getGenericReturnType();
                // 判断是否进行了 泛型类型参数化
                if (genericReturnType instanceof ParameterizedType) {
                    List<Object> objects = selectList(statementId, args);
                    return objects;
                }

                if ("findByCondition".equals(methodName)) {
                    return selectOne(statementId, args);
                } else if ("addUser".equals(methodName)) {
                    return addUser(statementId, args);
                } else if ("updateUser".equals(methodName)) {
                    return updateUser(statementId, args);
                } else if ("deleteUser".equals(methodName)) {
                    return deleteUser(statementId, args);
                } else {
                    throw new Exception("没有对应的statementId");
                }


            }
        });

        return (T) proxyInstance;
    }

}
